PURPOSE: To improve the network efficiency by collecting network diagnostic information from two systems and arranging line data so as to bridge a protocol between the two systems.

CONSTITUTION: X protocol data received from one Ethernet 5 in two Ethernet systems are processed by a central processing unit 7. The central processing unit 7 uses an X server program stored in a main memory 8 to write picture information to a video RAM 9 and data in the video RAM 9 are displayed on a CRT 3. Moreover, a protocol bridge type X terminal 1 receives data of other Ethernet 6 system, and data from the Ethernet 5 are given from a network interface 12 and data from the Ethernet 6 are given from a network interface 13 to an internal bus 11 of the protocol bridge X terminal 1 respectively. Then the line data of the two systems are processed by a network diagnostic section 14 and displayed on the CRT 3 by utilizing the X window processing section 2.